Non-fluorinated thermoplastic polymer / silicone elastomer coating

Abstract

The present invention relates to a coated heating element (1) for a household article, comprising a metal substrate (2) coated on at least one face (2a) with a coating (3) free of fluorocarbon resin and comprising at least the following layers and in this order from the metal substrate (2): (3a) a primer layer comprising one or more aromatic or heterocyclic thermoplastic polymers; (3b) one or more intermediate layer(s) comprising one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins;(3c) a finishing layer consisting of: - an elastomer silicone obtained from at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2), and at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H), preferably in the presence of a metal catalyst; and optionally: - one or more thermoplastic polymers, and / or - one or more additive(s), and / or - one or more coloring agents, the layer (3a) being different from at least one of the layers (3b).;

Description

Title of the invention: Non-fluorinated thermoplastic polymer / silicone elastomer coating

[0001] The invention applies in the field of non-stick coatings for household articles, heated or capable of being heated, in particular for kitchen articles and electrical cooking appliances.

[0002] PTFE (polytetrafluoroethylene) coated cookware is popular on the market because it allows cooking with little or no added fat and is easy to maintain. However, an inherent weakness of these coatings is their low mechanical strength, particularly when hot. Another inherent weakness of PTFE is its ductility, which results in coatings that are easy to mark, scratch, and wear with metal utensils (spatulas, forks, spoons, blender sticks, etc.).

[0003] To remedy this, numerous technical solutions have been proposed which consist of reinforcing the coating with hard fillers or by the interposition of hard sub-layers of inorganic or organic type.

[0004] In the case of primers reinforced with hard organic or inorganic fillers, significant improvements are indeed observed in abrasion resistance, but impacts to the metal are also observed when cooking food such as pork chops or when using metal spatulas.

[0005] In the case of hard inorganic bases such as for example those made from enamel or even metal oxides, the abrasion resistance is further improved and the impact problem is limited without however being eliminated.

[0006] Organic polymer undercoats are also known. These undercoats can effectively reduce the appearance of scratches considerably or even eliminate them. This strategy is therefore very interesting. The polymers used are very often thermoplastic polymers with high thermal resistance and a high melting point, such as polyaryletherketones and in particular oxy-1,4-phenylenephenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene or PEEK or phenylene sulfides.

[0007] The PEEK polymer is of interest in cookware since it has a high melting point (343°C) and excellent thermal stability under usage conditions at 260°C.

[0008] The following coating techniques can be carried out to obtain an undercoat from this type of polymer: spray coating, roller coating, curtain coating, by pad printing, screen printing, thermal projection, electrostatic spraying, inkjet.

[0009] Pure silicone resins are described as relatively non-stick and resistant to temperatures above 220-230°C. On the other hand, they are considered to have poor adhesion to the substrate.

[0010] Conversely, silicone-polyester resins are very widespread in molding because they are non-stick while being adherent to the substrate and compatible with stamping processes. However, they degrade at temperatures above 230°C. Indeed, the temperature range of use of cookware is between 50 and 250°C and it is not surprising to rise to temperatures of 300°C or even 350°C in the case of articles with induction bases. Their use is therefore not compatible with the temperatures of use in the field of cookware.

[0011] The present invention addresses the technical problem of improving the anti-adhesiveness of a coating with high thermo-mechanical properties.

[0012] The present invention also addresses the technical problem of replacement solutions for PTFE-type fluorinated resin-based coatings.

[0013] The present invention provides an alternative to predominantly PTFE-based coatings with a view to obtaining good resistance to mechanical wear of the coatings, in particular by kitchen utensils for culinary articles and thus improving the durability of their mechanical resistance, in particular when hot and / or their cleanability, in order to extend the life of the article. DEFINITIONS

[0014] The term "layer" is understood to mean, within the meaning of the present invention, a continuous or discontinuous layer. A continuous layer (or also called a monolithic layer) is a single whole forming a total flat area completely covering the surface on which it is placed. A discontinuous layer (or non-monolithic layer) may comprise several parts, thus not being a single whole.

[0015] The term "base coat", "primer coat", "bonding coat" or "bonding primer" means all the layers from the first layer applied directly to the support (it is preferable that this layer adheres well to the support and provides all its mechanical properties to the coating: hardness, scratch resistance) to the last layer before the first intermediate or decorative layer. The first layer of the coating is a primer layer.

[0016] The term "intermediate layer" means the layers inserted between the primary layer(s) and the finishing layer(s). The intermediate layer(s) may be "decorations" or "decorative layers". The intermediate layer(s) is / are not intended to be in contact with food.

[0017] The term "finishing layer" or "finish" means a continuous surface layer applied after the intermediate layer(s) if the coating comprises one or more intermediate layer(s) or after the primary layer(s). The last layer of the coating is a finishing layer. Usually, at least the last finishing layer, or even all the finishing layers, is / are transparent to allow visibility of the underlying layers, in particular when the underlying layers are decorative layers. The finishing layer(s) protect the underlying layers from mechanical attack and give the coating its non-stick properties. Preferably, in the case of a culinary item or electrical cooking appliance, the last finishing layer is intended to be in contact with food.

[0018] The term "decor" or "decorative layer" means one or more continuous or discontinuous layers comprising a pigment composition. The decor may be in the form of one or more patterns, of one or more colors. A decor is clearly visible to the user with the naked eye and at a conventional distance for using the household item.

[0019] "Overlapping layers" means partially or completely superimposed layers. These layers may be in the form of partially overlapping patterns, for example concentric discs.

[0020] “Adjacent layers” means non-overlapping layers. These layers may be in the form of identical or different non-overlapping patterns, preferably uniformly distributed.

[0021] The term "temperature reference pigment composition" means a composition comprising a pigment which, at a given temperature, makes it possible to indicate to the user that the optimum usage temperature has been reached. This indication is made by comparing the colours of the thermochromic pigment composition and the temperature reference pigment composition. Either the optimum usage temperature is reached when the colours are identical, or the optimum usage temperature is reached when the colours are visually very different.

[0022] The “temperature reference pigment composition” may comprise a pigment which has:

[0023] - the same color as the thermochromic pigment composition at the temperature optimal use,

[0024] * either because this pigment has the same color at room temperature as the thermochromic pigment composition at the optimum operating temperature and does not change color with temperature,

[0025] * either because this pigment has a different color at room temperature of that of the thermochromic pigment composition which evolves to the same color than the thermochromic pigment composition at the optimum operating temperature,

[0026] - a color very different from that of the thermochromic pigment composition at the optimal temperature of use, whether this pigment changes color or not with the evolution of the temperature.

[0027] The optimum use temperature can be achieved when the color of the temperature reference pigment composition corresponds to a color indicated in the user guide for the household article comprising the coating of the invention or to a color indicated on a color scale provided to the user with said article.

[0028] The temperature reference pigment composition is thermochromic or thermostable.

[0029] The temperature reference pigment composition may be, for example, a cooking temperature reference pigment composition or an indication of the risk of overheating.

[0030] The expression "thermochromic semiconductor" is understood to mean, within the meaning of the present invention, a mineral or organic compound which exhibits a reversible change in color upon increasing temperature. The progressive and reversible thermochromic nature of these semiconductor compounds is linked to the reduction in the width of the forbidden band of the semiconductor due to the expansion of the material. Indeed, the periodicity of the network of anions and cations leads to the gathering of energy levels into energy bands. The filled energy band with the highest energy is called the valence band and the empty energy band with the lowest energy is called the conduction band. Between these two bands, there is a forbidden band called the gap.The color of a semiconductor material can come from the presence of a charge transfer which corresponds to the passage of an electron either from a valence band to a conduction band on the same atom, or commonly from the orbital of an anion to the orbital of a cation (interatomic photonic absorption).

[0031] In the fields of application envisaged for the present invention, the optimal conditions are reached when the coating reaches a temperature suitable for cooking food, preferably between 100 and 250°C.

[0032] By "thermochromic pigment or pigmentary composition", it is meant, within the meaning of the present invention, a pigment or a pigmentary composition which changes color depending on the temperature in a given temperature range, this change being reversible. This change in color is visible to the user with the naked eye and at a conventional operating distance.

[0033] The term "thermostable pigment" means a pigment which does not exhibit a change in color when subjected to an increase in temperature in a given temperature range or which exhibits a change in color when subjected to a temperature rise in a given temperature range so low that it is not visible to the user with the naked eye and at a conventional operating distance.

[0034] Preferably, the thermostable pigments have a color difference AE* between 25°C and 200°C of less than 10, AE* being defined by the CIE1976 formula in the CIELAB color space:

[0035] , r : ; ; ,x2 / AE -y(^2 ) + P2 "^1 )2

[0036] Li*, ai* and bi* characterizing the L*a*b values ​​of said compound at room temperature

[0037] L2*, a2* and b2* characterizing the L*a*b values ​​of said compound at 200°C.

[0038] By "the colors are identical" we mean indistinguishable by the user with the naked eye and at a conventional operating distance.

[0039] By the expression "culinary article", it is necessary to understand within the meaning of the present invention an object intended to cook and to be heated by an external heating system such as frying pans, saucepans, sauté pans, woks, barbecue grills. A culinary article is capable of transmitting the heat energy provided by this external heating system to a material or food in contact with said object.

[0040] By the expression "electric cooking appliance", it is necessary to understand within the meaning of the present invention a heating object having its own heating system such as an electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread machine, electric pressure cooking appliance.

[0041] The term "coating" means all the layers adhering to the metal substrate and covering this substrate. The coating according to the invention obtained is advantageously solid, "solid" means the characteristic of a cohesive material insoluble in water, in usual solvents, in food components such as aqueous or fatty mixtures, even if the material may have great hardness or great flexibility such as an elastomer.

[0042] In the present invention, the % by weight are expressed in dry weight, i.e. without solvent. Summary of the invention

[0043] A first subject of the invention relates to a coated heating element (1) for a household article, comprising a metal substrate (2) coated on at least one face (2a) with a coating (3) free of fluorocarbon resin and comprising at least the following layers and in this order from the metal substrate (2):

[0044] (3a) a primer layer comprising one or more thermoplastic polymers aromatic or heterocyclic;

[0045] (3b) one or more intermediate layer(s) comprising one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins;

[0046] (3c) a finishing layer consisting of:

[0047] - of a silicone elastomer obtained from at least one carrier organopolysiloxane of reactive vinyl functions (-CH=CH2), and at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H), preferably in the presence of a metal catalyst; and optionally:

[0048] - of one or more thermoplastic polymers, and / or

[0049] - one or more additive(s), and / or

[0050] - one or more coloring agents.

[0051] the layer (3a) being different from at least one of the layers (3b).

[0052] Another object of the invention relates to a method of manufacturing a household article comprising a heating element coated (1) with a coating (3) according to the invention characterized by the following steps:

[0053] a) a step of providing a metal substrate (2) in the form of a substantially flat metal substrate comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22);

[0054] b) where appropriate, when a metal substrate in the form of a substantially flat metal substrate is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22), said step (b) being carried out either before step (a), or before step (d) of producing the layers (3a) and (3b) of the coating (3), or after step (f) of baking and before step (g) of producing the finishing layer or after step (g);

[0055] c) optionally, a step of treating at least one face (2a) of the metal substrate (2), to obtain a treated face (2a) promoting the adhesion of a primer layer (3a) on the support (2);

[0056] d) a step of applying the layers (3a) (3b) of the coating (3);

[0057] e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b);

[0058] f) optionally a step of cooking the element obtained in step d) at a temperature between 250°C and 420°C;

[0059] g) a step of applying the finishing layer (3c) to the element obtained in step d), e) or f);

[0060] h) optionally a step of cooking the element obtained in step g) at a temperature between 250°C and 420°C.

[0061] Another object of the invention relates to a household article comprising a coated heating element (1) according to the invention or capable of being obtained according to the method of the invention. FIGURES

[0062] [Fig. 1]: diagram of a cooking element according to the invention with the layer (3b) being continuous and covering the entire layer (3a)

[0063] [Fig.2] ; diagram of a cooking element according to the invention with the layer (3b) not covering the entire layer (3a) and forming a decoration

[0064] [Fig.3] diagram of cooking element according to the invention with layer (3b) consisting of two decorations (i) and (j)

[0065] [Fig.4] ; Pattern distribution diagram. 4A = adjacent non-overlapping patterns. 4B = partially overlapping patterns. 4C = overlapping patterns.

[0066] [Fig.5] diagram of a culinary article according to the invention

[0067] [Fig.6] diagram of an electrical cooking appliance according to the invention DETAILED DESCRIPTION

[0068] A first subject of the invention relates to a coated heating element (1) for a household article, comprising a metal substrate (2) coated on at least one face (2a) with a coating (3) free of fluorocarbon resin and comprising at least the following layers and in this order from the metal substrate (2):

[0069] (3a) a primer layer comprising one or more thermoplastic polymers aromatic or heterocyclic;

[0070] (3b) one or more intermediate layer(s) comprising one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins;

[0071] (3c) a finishing layer consisting of: - an elastomer silicone obtained from at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2), and at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H), preferably in the presence of a metal catalyst; and optionally: - one or more thermoplastic polymers, and / or - one or more additive(s), and / or - one or more coloring agents.

[0072] the layer (3a) being different from at least one of the layers (3b).

[0073] Advantageously, the layers (3a), (3b) and (3c) form a coating (3) which covers the metal substrate (2). This coating (3) has non-stick properties and forms a non-stick coating, which non-stickness is particularly conferred by the layer (3c).

[0074] Advantageously, the layer (3a) is in contact by one of its faces with the metal substrate (2) by its face (2a).

[0075] When the household item is a kitchen item or an electrical cooking appliance, the coated face (2a) of the metal substrate forms a cooking face. In other words, the coating (3) according to the invention is then intended to be in contact with food. Advantageously, the finishing layer (3c) is then in contact by one of its faces with food and thus forms a cooking face (5).

[0076] The coating (3) according to the invention does not comprise fluorocarbon resin, also called fluorinated polymer or fluoropolymer. In other words, said coating (3) is free of fluorocarbon resin. Thus, the coating (3) does not comprise or emit perfluoroalkyl and polyfluoroalkyl compounds.

[0077] Advantageously, the thickness of the layer(s) (3a) and (3b) is between 1 μm and 100 μm, preferably between 2 μm and 30 μm, particularly preferably between 3 μm and 10 μm.

[0078] Advantageously, the thickness of the layer (3c) is between 0.1 μm and 10 μm, preferably between 0.5 mm and 5 mm, even more preferably between 1 and 2 mm.

[0079] Advantageously, the content of aromatic or heterocyclic thermoplastic polymers in the primer layer (3a) is lower than the content of aromatic or heterocyclic thermoplastic polymers in the layer(s) (3b). Preferably, according to this embodiment, the content of aromatic or heterocyclic thermoplastic polymers increases from the primer layer (3a) to the last layer (3b).

[0080] LAYERS (3a) and (3b)

[0081] The primer layer (3a) comprises one or more aromatic or heterocyclic thermoplastic polymers.

[0082] The intermediate layer(s) (3b) comprises / comprise one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins.

[0083] Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises / comprise from 20% to 100% by weight of one or more aromatic or heterocyclic thermoplastic polymers relative to the weight of said layer.

[0084] Advantageously, the content of aromatic or hetero thermoplastic polymers cyclics of the primer layer (3a) represents from 50 to 75% by weight of the primer layer (3 a).

[0085] Advantageously, the content of aromatic or heterocyclic thermoplastic polymers in the intermediate layer(s) (3b) represents from 75 to 100% by weight of said layer(s).

[0086] At least one intermediate layer (3b) is present in the coating (3) according to the invention. Advantageously, the at least one intermediate layer (3b) is different from the primer layer (3a). More preferably, in this case, all the intermediate layers (3b) are different from the primer layer (3a). Advantageously, the primer layer (3a) is different from all the intermediate layers (3b).

[0087] Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises / comprise one or more fillers. According to this embodiment, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises / comprise less than 40%, preferably less than 30%, by weight of fillers relative to the total weight of said layer, preferably between 5 and 25% by weight.

[0088] According to one embodiment, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises one or more acrylic resin(s). The acrylic resin(s) is / are advantageously chosen from the group consisting of polymers resulting from an emulsion polymerization of different monomers with other acrylic-based monomers.

[0089] According to one embodiment, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises / comprise one or more coloring agent(s). Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises / comprise less than 30%, preferably less than 20%, by weight of one or more coloring agent(s) of the total weight of said layer.

[0090] Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) further comprises / comprise water and / or one or more solvents, preferably unlabeled, for example propionamide, N-formylmorpholine (NFM), N-Methyl Imidazole (NMI), N-ButylPyrrolidone (NBP), dimethyl sulfoxide (DMSO), or alcoholic, for example Propylene Glycol (PPG), Diethylene glycol, di propylene glycol butyl ether (DPNB).

[0091] Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises / comprise one or more surfactants.

[0092] Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) further comprises one or more anti-foaming agents.

[0093] According to one embodiment, the primer layer (3a) is made up of one or more aromatic or heterocyclic thermoplastic polymers and optionally: - one or more additives, and / or, - one or more coloring agent(s), and / or - one or more filler(s).

[0094] According to one embodiment, the intermediate layer(s) (3b) is / are made up of one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins and optionally: - one or more additives, and / or, - one or more coloring agent(s), and / or - one or more filler(s).

[0095] LAYER (3c)

[0096] The finishing layer (3c) consists of: - an elastomer silicone obtained from at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H), preferably in the presence of a metal catalyst; and optionally: - one or more thermoplastic polymers, and / or - one or more additive(s), and / or - one or more coloring agents.

[0097] The elastomeric silicone of layer (3c) forms a network which can be made up of a combination of 4 simple organosiloxane units called M, D, T and Q depending on the degree of substitution by oxygen of the silicon atom, as described in the following table, where R is an organic substituent described below.

[0098] [Tables 1] Structure - Degree of substitution by oxygen | 1 Symbol MR —o-sLo—■ R ■ D $ : 3 T' ' ' s 1 Q

[0099] The precursors of the elastomer are organopolysiloxanes. These macromolecules are formed of M, D, T, and / or Q units as described in the table, where R is independently an alkyl group, in particular methyl, or aryl, in particular phenyl, different natures of R being able to be present on the same macromolecule.

[0100] Organopolysiloxanes can be either linear or weakly branched (majority of D groups). Linear or weakly branched organopolysiloxanes are generally liquid, more or less viscous at room temperature, and are called silicone oils.

[0101] The organopolysiloxanes carrying reactive functions of layer (3c) are precursors which react by a crosslinking which is a polyaddition (or hydrosilylation). This crosslinking is carried out by reaction between the reactive vinyl functions (-CH=CH2) present on one of the organopolysiloxanes and the reactive silyl hydride functions (Si-H) present on the other organopolysiloxane mixed with the first.

[0102] This crosslinking can be done by thermal activation, or chemical activation using a catalyst.

[0103] Advantageously, the organopolysiloxanes carrying reactive functions of layer (3c) are silicone oils.

[0104] The reactive functions are present on each organopolysiloxane in the number of at least one and can be present in the number of 2, 3, or more ... as much as the molecular structure allows. Silicone oils comprising at least one reactive function are called "reactive oils". The reactive functions can be found either at the end of the macromolecular chain (termination), or distributed over the chain.

[0105] The addition of a catalyst may be necessary for crosslinking: this may be, for example, platinum or a suitable platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0106] THERMOPLASTIC POLYMERS

[0107] Advantageously, the thermoplastic polymer(s) is / are chosen from the group consisting of aromatic thermoplastic polymer(s) such as polyaryletherketone(s) (PAEK), poly(arylethersulfones) (PAES), poly(arylene sulfides) (PAS) or poly(phenylene oxide) (PPO), liquid crystal polymers, heterocyclic thermoplastic polymers and mixtures thereof.

[0108] PAEK

[0109] Advantageously, the polyaryletherketone(s) (PAEK) is (are) chosen from the group consisting of: polyetherketones (PEK), polyetheretherketone (PEEK), poly-etherketoneketones (PEKK), polyetheretherketoneketones (PEEKK) and polyetherketo-neetherketoneketones (PEKEKK), particularly preferably is (are) PEEK.

[0110] Other aromatic thermoplastic polymers

[0111] As aromatic thermoplastic polymer(s), examples which are suitable according to the invention are poly(phenylene oxide) (PPO), poly(arylethersulfone) polymer (PAES), and in particular polyethersulfone (PES), poly-phenylene ether sulfone (PPSU), poly(arylene sulfides) (PAS) and in particular polyphenylene sulfide (PPS), liquid crystal polymers and mixtures thereof.

[0112] Heterocyclic thermoplastic polymers

[0113] As heterocyclic thermoplastic polymers, polyetherimides (PEI), polyimides (PI), polyamideimides (PAI) and polybenzymidazole (PBI), or mixtures thereof, are cited as examples suitable according to the invention.

[0114] Advantageously, the thermoplastic polymer(s) is / are chosen from the group consisting of polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyamideimide (PAI), polyimide (PI), poly(phenylene oxide) (PPO), poly(arylene sulfide) (PAS), polyetherimide (PEI), polybenzymidazole (PBI), liquid crystal polymers (LCP), polyphenylene sulfide (PPS), polyarylether ketone (PAEK) including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK) and mixtures thereof.

[0115] According to one variant, the PAEK is implemented in the form of a suspension and the PAEK particles in the PAEK suspensions have a particle size with a d50 of approximately 10 pm to 15 pm.

[0116] Advantageously, the nature of the thermoplastic polymer(s) in the layers (3a), (3b) and (3c) may be identical or different.

[0117] Advantageously, the layer (3b) comprises one or more thermoplastic polymer(s), preferably in a proportion by weight of said layer of less than 50%, preferably 40%.

[0118] Advantageously, the layer (3a) comprises one or more thermoplastic polymer(s), preferably in a proportion by weight of said layer of less than 30%, preferably 20%.

[0119] Advantageously, the layer (3b) comprises one or more thermoplastic polymer(s), preferably in a proportion by weight of said layer of less than 50%, preferably 40%.

[0120] Advantageously, the layer (3c) comprises one or more thermoplastic polymer(s), preferably in a proportion by weight of said layer of less than 15%, preferably 10%.

[0121] According to one embodiment, the layer (3a) and the layer (3b) comprise one or more thermoplastic polymer(s), the proportion of thermoplastic polymer(s) in the layer (3b) being preferentially greater than the proportion of thermoplastic polymer(s) in the layer (3a).

[0122] CHARGES

[0123] The fillers within the meaning of the invention make it possible to provide mechanical reinforcement and can also provide hydrophobicity properties, while improving the mechanical resistance and thermal conductivity of the coating.

[0124] Fillers do not only have the function of providing color to the coating, but can contribute to it.

[0125] Advantageously, the filler(s) is / are chosen from the group consisting of ceramic fillers (SiO2, etc.) and / or mineral and / or metallic fillers (A12O3, TiO2, etc.) and / or silicas and / or diamond particles.

[0126] Preferably, the filler(s) is / are chosen from the group consisting of metal oxides, metal carbides, metal oxynitrides, metal nitrides, and mixtures thereof.

[0127] Advantageously, said metal is a transition metal, such as at least one of the elements chosen from B, Ni, Ti, Zr or Hf.

[0128] More preferably, the filler(s) is / are chosen from the group consisting of:

[0129] - fillers for reinforcement: organic or inorganic hard fillers; the fillers inorganic hard particles are preferably particles of silicon carbides or alumina or zirconia or graphite, or ceramics, or carbonate, or hydrated alumina, aluminum trihydroxide or one or more metal oxide(s), graphite, graphene;

[0130] - other fillers for reinforcement chosen from metal oxides: silica, micas, lamellar fillers, clays such as montmorillonite, sepiolite, gypsite, kaolinite and laponite, zinc dioxide, quartz, and zirconium phosphate, alumina, zirconia, zinc oxide, copper oxide, iron oxide;

[0131] - fillers chosen from reinforcing fibers: glass or carbon fiber or aramid;

[0132] - conductive fillers comprising a transition metal carbide and / or a nitride of transition metal: characterized in that the transition metal is at least one of the elements chosen from B, Ni, Ti, Zr or Hf;

[0133] for example: Cubic Boron Nitride, diamond particles, metal particles;

[0134] - lamellar fillers capable of conferring lubricating properties, such as example clays, graphene or graphite.

[0135] Among the fillers in combination with silicone resins, the preferred fillers are:

[0136] - reinforcing fillers: silica or carbonates with minimum filler rates 10-15% / wt and up to 60% / wt,

[0137] - alumina, hydrated alumina, aluminum trihydroxide,

[0138] - silica (precipitated or pyrogenic) with a d50 <0.1 pm and a specific surface area BET > 30 m2 / g and preferably between 30 and 500 m2 / g,

[0139] - or mixture of quartz and silica, diatomaceous earth or ground quartz, titanium, mica, talc, kaolin, barium sulfate, slaked lime, zinc oxide, expanded vermiculite, unexpanded vermiculite, calcium carbonate etc.

[0140] More preferably, the filler(s) is / are chosen from the group consisting of alumina, silicon carbide, tungsten carbide, boron nitride, quartz, and mixtures thereof.

[0141] Advantageously, the fillers present in the primer layer(s) (3a) or the intermediate layer(s) (3b) are inorganic hard fillers, preferably metal oxides, carbides, nitrides, preferably alumina, silicon carbides or fumed silica.

[0142] Certain inorganic hard fillers such as silicon carbide, in addition to their mechanical reinforcement performance, also have the advantage of being conductive fillers and therefore provide excellent thermal conductivity.

[0143] The addition of this type of filler makes it possible to improve the culinary rendering with better diffusion of heat from the metal substrate to the food in contact with the coating.

[0144] Advantageously, the average diameter d50 of the charges is between 0.1 and 50 pm, advantageously still between 5 and 15 pm.

[0145] Advantageously, the proportion of fillers in a layer is between 0.5 and 30% by dry weight relative to the total weight of said layer after cooking, preferably between 5 and 20%.

[0146] Advantageously, the proportion of fillers in the layer (3a) is greater than 20% by weight, preferably greater than 30% by weight, relative to the total weight of said layer.

[0147] Advantageously, the proportion of fillers in layers (3a) and (3b) may be identical or different.

[0148] Advantageously, the nature of the charges in layers (3a) and (3b) may be identical or different.

[0149] ADDITIVES

[0150] Advantageously, said additives are chosen from the group consisting of anti-foam agents, dispersing agents, wetting agents, thickeners, pH adjusters, reactive silicone oils.

[0151] Said anti-foaming agent(s) are preferably chosen from the group consisting of mineral oils, diols, hydrocarbons, glycerides, oxirane, emulsified fatty acids.

[0152] The surfactant(s) is (are) preferentially chosen from the group consisting of glycol ether, ethoxylated alcohol excluding alkyl phenol ethoxylates (APE), gemini surfactants.

[0153] The dispersing agent(s) is (are) preferentially chosen from the group consisting of anionic dispersants such as fatty acid derivatives.

[0154] Said thickeners are preferably chosen from the group consisting of acrylic-based or polyurethane-based copolymer, cellulose, pyrogenic silica.

[0155] Said pH adjusters are preferably chosen from the group consisting of Bronsted bases: ammonia, amines (triethylamine, triethanolamine, etc.), hydroxides (soda, potash, etc.), carbonates.

[0156] Advantageously, the proportion of additives in the layer (3a) is less than 1% by weight relative to the total weight of said layer.

[0157] Advantageously, the proportion of additives in the layer (3c) is less than 20% by weight relative to the total weight of said layer.

[0158] COLOURING AGENTS

[0159] Advantageously, the coloring agent(s) is / are chosen from the group consisting of thermochromic pigments, thermostable pigments, glitter, preferably hologram glitter, and mixtures thereof.

[0160] Advantageously, the proportion of coloring agents in layers (3a), (3B) and (3c) is between 0.5 and 50% by dry weight relative to the total weight of said layer after cooking.

[0161] Advantageously, the proportion of coloring agents in layers (3a) and (3b) ranges from 10% to 40% by weight relative to the total weight of said layer.

[0162] Advantageously, the proportion of coloring agents in the layer (3c), when they are present, is less than 10% by weight relative to the total weight of said layer.

[0163] Advantageously, the proportion of coloring agents in layers (3a), (3b) and (3c) may be identical or different.

[0164] Advantageously, the nature of the coloring agents in layers (3a), (3b) and (3c) may be identical or different.

[0165] Advantageously, the layer (3c) is transparent. In this case, if it comprises coloring agents, these coloring agents are glitter. Thermochromic pigments

[0166] Preferably, the thermochromic pigment(s) is / are chosen from the group consisting of Bi2O3, Fe2O3, V2O5, WO3, CeO2, In2O3, Yi^CaojeTii^VojeCW Agi, (Bil x Aj(V|VMjO4avcc - x is equal to 0 or x is between 0.001 and 0.999, - y is equal to 0 or y is between 0.001 and 0.999, - A and M are selected from the group consisting of nitrogen, phosphorus, an alkali metal, an alkaline earth metal, a transition metal, a metal poor, a metalloid or a lanthanide, - A and M are different from each other.

[0167] Knowing that A and M are different from each other, when:

[0168] - A is an alkali metal, it can be chosen from Li, Na, K, Rb, Cs,

[0169] - M is an alkali metal, it can be chosen from Li, Na, K, Rb, Cs,

[0170] - A is an alkaline earth metal, it can be chosen from Be, Mg, Ca, Sr, Ba,

[0171] - M is an alkaline earth metal, it can be chosen from Be, Mg, Ca, Sr, Ba,

[0172] - A is a transition metal, it can be chosen from Sc, Ti Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir,

[0173] - M is a transition metal, it can be chosen from Sc, Ti Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir,

[0174] - A is a poor metal, it can be chosen from Al, Zn, Ga, In, Sn,

[0175] - M is a poor metal, it can be chosen from Al, Zn, Ga, In, Sn,

[0176] - A is a metalloid, it can be chosen from B, Si, Ge, Sb,

[0177] - M is a metalloid, it can be chosen from B, Si, Ge, Sb,

[0178] - A is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,

[0179] - M is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

[0180] Preferably, A and M different from each other are B and / or Mg.

[0181] Preferably, the pigment (Bii_xAx)(Vi_yMy)04 has a monoclinic scheelite crystallographic form at room temperature.

[0182] Preferably, x and y are 0, i.e. the pigment (Bii.xAx)(Vi yMy)O4 is Bismuth Vanadate (BiVO4). Advantageously, a BiVO4 with a monoclinic scheelite crystallographic structure at room temperature is used.

[0183] Bismuth Vanadate is a yellow inorganic compound with the formula BiVO4, widely used for its color properties and its lack of toxicity. Registered in the Colour Index International database as QI Pigment Yellow 184, it is marketed by Heubach (Vanadur®), BASF (Sicopal®), FERRO (Lysopac) and Bruchsaler Farbenfabrik (Brufasol®). Thermostable pigments

[0184] Preferably, the thermostable pigment(s) is / are chosen from the group consisting of:

[0185] - Yellow titanium rutile pigment,

[0186] - Yellow pigment derived from bismuth, for example selected from vanadates of stabilized bismuth (Py i84)

[0187] - Red pigment, for example selected from perylene red (for example PR149, PR178 and PR224), iron oxide,

[0188] - Orange pigment of bismuth oxyhalides type (PO85),

[0189] - Bismuth vanadate orange pigment (PO86)

[0190] - Zinc tin titanium orange pigment (PO82)

[0191] - Cerium sulfide orange pigment (PO75; PO78)

[0192] - Orange-yellow pigment of the antimony titanium chrome rutile type (PBr24)

[0193] - Orange-yellow pigment of tin and zinc rutile type (Py2i6)

[0194] - Niobium tin zinc sulfide orange-yellow pigment (Py227)

[0195] - Orange-yellow pigment of double oxides of tin and niobium

[0196] - Co3(PO4)2

[0197] - LiCoPO4

[0198] - CoA12O4

[0199] - Cr2O3

[0200] - TiO2

[0201] - Black pigment PBk28 (Copper chromite black spinel)

[0202] - and their mixtures. Decors

[0203] According to one embodiment, the layer(s) (3b) is(are) continuous and covers the entire layer (3a) (see [Fig.l]).

[0204] According to another embodiment, the layer(s) (3b) do(es) not cover the entirety of the layer (3a) and form(s) at least one decoration (see [Fig.2]).

[0205] Advantageously, the layer(s) (3b) compose several decorations, one (i) comprising one or more thermochromic pigment(s) and the other (j) comprising at least one temperature reference pigment composition (see [Fig.3]).

[0206] According to one embodiment, each of the two decorations (i) and (j) is in the form of adjacent non-overlapping patterns. For example, each decoration is represented by different geometric patterns distributed uniformly over the entire surface and alternating with respect to each other (see Figure 4A).

[0207] According to another embodiment, the two decorations (i) and (j) are partially overlapping. For example, each decoration is represented by different geometric patterns distributed uniformly over the entire surface and partially overlapping (see Figure 4B).

[0208] Preferably, the two decorations (i) and (j) are overlapping, either because one of the two decorations is a continuous layer and the other decoration covers it in the form of patterns, or because the two decorations (i) and (j) are in the form of overlapping patterns (see Figure 4C). Sequins

[0209] The flakes that can be used in the context of the present invention can be independently chosen from mica flakes, coated or not, silica flakes, coated or not, aluminum flakes, coated or not, iron oxide flakes, coated or not. Mica or silica flakes coated with titanium dioxide. The flakes that can be used in the context of the present invention can be treated to give a particular color effect.

[0210] Advantageously, the flake(s) is / are particles chosen from the group consisting of particles of mica, aluminum, mica coated with titanium dioxide or mixtures thereof. Hologram sequins

[0211] Advantageously, the glitter(s) is / are hologram glitter, i.e. a mixture of magnetizable particles and non-magnetizable particles.

[0212] The magnetizable particles may advantageously be particles comprising at least one ferromagnetic metal. These magnetizable particles may be of a homogeneous nature, i.e. made of the same material, or of a composite nature, i.e. these magnetizable particles have a core-shell structure, in which the ferromagnetic metal is found in the core and / or in the shell of said particles. Examples of composite magnetizable particles include mica flakes coated with iron oxide Fe2O3 or stainless steel fibers coated with a sol-gel material, as protection against corrosion during the steps of implementing the coating, or else plastic flakes coated with iron oxide Fe2O3, or flakes whose core is made of ferromagnetic metal and the shell is formed of a plastic material or a sol-gel material.

[0213] According to one embodiment, a portion of said magnetizable particles is oriented so as to form a three-dimensional decoration.

[0214] Advantageously, the mixture of magnetizable particles and non-magnetizable particles represents between 1% and 5% by weight of the weight of the layer, preferably between 2% and 3% by weight.

[0215] Advantageously, the percentage of non-magnetizable particles in the mixture of magnetizable particles and non-magnetizable particles is between 15% and 40% by weight relative to the total weight of the mixture of magnetizable particles and non-magnetizable particles.

[0216] Advantageously, the magnetizable particles have a dimension D50 less than or equal to 23 pm.

[0217] By the term “D50” is meant, within the meaning of the present invention, the maximum dimension presented by 50% of the particles in number.

[0218] Advantageously, the non-magnetizable particles have a dimension D90 between 20% and 250% of the D90 dimension of the magnetizable particles.

[0219] By the term “D90” is meant, within the meaning of the present invention, the maximum dimension presented by 90% of the particles in number.

[0220] Advantageously, the magnetizable particles and / or the non-magnetizable particles are colored on the surface.

[0221] Advantageously, the non-magnetizable particles consist of mica, aluminum, or mica coated with titanium dioxide.

[0222] Advantageously, the magnetizable particles consist of iron, iron oxide, iron-coated aluminum, or iron-coated mica, the iron being in ferritic form.

[0223] SILICONE RESINS

[0224] In the text of the description, the expression "silicone resin" is used indifferently to refer to the silicone before its crosslinking or after its crosslinking. In the text of the description, the expression "silicone" designates an organo-lysiloxane material. Crosslinking is the step which makes it possible to transform the silicone into an insoluble material, for example by polyaddition, polycondensation or dehydrogenation. Crosslinking is carried out from precursors which are generally silicone oils or resins, which crosslink to obtain a three-dimensional network forming a material called silicone resin, in the description.

[0225] This crosslinking can be done by thermal activation, or chemical activation using a catalyst, such as platinum.

[0226] The silicone resins can be obtained from precursors, advantageously soluble in a solvent or in emulsion in water, such as oils or crosslinkable resins, in particular chosen from: a silicone hydride, a silicone oil resin comprising at least one vinyl group (-CH=CH2), a silicone or silicone-polyester resin (copolymer) comprising at least one alkoxy group, for example methoxy or ethoxy, and / or a silicone or silicone-polyester resin (copolymer) comprising at least one alkoxy group, in particular ethoxy, or a hydroxy group and mixtures thereof. These precursors have the capacity to crosslink in order to obtain a silicone resin which is characterized by its insolubility and its substantially solid form.

[0227] Advantageously, these precursors are polymeric or oligomeric, either in the form of silicone oils with a variable degree of branching, or in the form of silicone resins with a variable degree of pre-crosslinking or copolymers of silicone resins such as silicone-polyester, silicone-alkyd, silicone-polyurethane, silicone-epoxy resins, or in the form of a mixture of silicone oils, silicone resins and copolymers of silicone resins. The silicon atoms may be substituted by alkyl (in particular methyl) or aryl (in particular phenyl) groups or mixtures thereof. The oils or resins preferably comprise one or more (2, 3 or plus) hydroxy or alkoxy (in particular methoxy, ethoxy, butoxy) functional groups as substituents of silicon atoms.

[0228] Advantageously, the silicone resin(s), obtained after crosslinking their precursors, i.e. crosslinked, is / are chosen from the group consisting of methyl silicone and / or phenyl silicone and / or methyl-phenyl-silicone resins, methyl silicone-polyester resin (copolymers), phenyl silicone-polyester resin (copolymers), methyl-phenyl silicone-polyester resin (copolymers), silicone-alkyd resin (copolymers), modified silicone resin and mixtures thereof.

[0229] Advantageously, the silicone resin(s) is / are chosen from the group consisting of methyl silicone and / or phenyl silicone and / or methyl-phenyl-silicone resins, methyl silicone-polyester resin (copolymers), phenyl silicone-polyester resin (copolymers), methyl-phenyl silicone-polyester resin (copolymers), silicone-alkyd resin (copolymers), modified silicone resin and mixtures thereof.

[0230] The silicone resins can be obtained from precursors, notably chosen from: a silicone hydride, a silicone resin comprising at least one vinyl group (-CH=CH2), a silicone-polyester resin (copolymer) comprising at least one methoxy group, and / or a silicone-polyester resin (copolymer) comprising at least one ethoxy group, and mixtures thereof.

[0231] The silicone resin forms a network which may consist of a combination of 4 simple organosiloxane units called M, D, T and Q depending on the degree of substitution by oxygen of the silicon atom, as described in the following table, where R is an organic substituent described below.

[0232] [Tables2] | Structure üegrë of substitution Symbol by oxygen § St.$!" Ô"" $ 5¾ — 1 | M 2- ] D ? ■ 1 ■ to: ô 4 Q

[0233] The organopolysiloxane material or polymer is obtained by crosslinking from precursors which can be monomeric or polymeric, or intermediately which can be oligomeric. The organopolysiloxane polymer can also be obtained from a mixture of these different kinds of precursors. When the network contains a higher number of T and Q units, than D, the crosslinking density is higher. The distribution between the M, D, T and Q units depends on the chemical structure of the precursors, in particular on this M, D, T, Q distribution within the precursors.

[0234] The polymeric precursors are organopolysiloxanes. These macromolecules are formed from M, D, T, and / or Q units as described in the table, where R is independently an alkyl group, in particular methyl, or aryl, in particular phenyl, it being possible for different natures of R to be present on the same macromolecule.

[0235] Organopolysiloxanes can be either linear or slightly branched (majority of D groups), or branched or highly branched (majority of T and Q groups). Linear or lightly branched organopolysiloxanes are generally liquid, more or less viscous at room temperature, and are called silicone oils. Branched or highly branched (pre-crosslinked) organopolysiloxanes constitute a network at the scale of the individual macromolecule and are called silicone resins. At room temperature, the resins are substantially in solid form, or in liquid form provided in particular that they have a fairly low molecular weight, in the form of a solution in a solvent or in the form of an aqueous emulsion. They can be copolymerized with organic polymers or oligomers not containing silicon, chosen in particular from polyesters, acrylics, alkyds, polyurethanes, epoxy resins.

[0236] When the crosslinking is a hydrolysis-polycondensation: it is carried out thanks to the reactive hydroxy or alkoxy functions, in particular methoxy, ethoxy or butoxy, present on the organopolysiloxane.

[0237] When the crosslinking is a polyaddition (or hydrosilylation): it is carried out by reaction between the reactive vinyl functions (-CH=CH2) present on one of the organopolysiloxanes and the reactive silyl hydride functions (Si-H) present on the other organopolysiloxane mixed with the first.

[0238] All these reactive functions are present on each organopolysiloxane in the number of at least one and can be present in the number of 2, 3, or more ... as much as the molecular structure allows. Silicone oils comprising at least one reactive function are called "reactive oils". The reactive functions can be found either at the end of the macromolecular chain (termination), or distributed over the chain.

[0239] Silicone-polyester resins in particular have silicone / polyester mass ratios of, for example, 90 / 10, 80 / 20, 70 / 30, 60 / 40, 50 / 50, 40 / 50, 30 / 70, 20 / 80, 10 / 90, advantageously between 80 / 20 and 50 / 50.

[0240] Linear PDMS silicone oils, pure or pre-emulsified in water, are characterized firstly by their molecular mass, which is a direct increasing function of the viscosity of the pure oil. They are then characterized by the presence or absence of reactive functions, for example hydroxyls on the silicon atoms (silanol), their number and their location on the molecular chain. For example, reactive oils with viscosities of between 50 and 20,000 mPa.s, and in particular between 300 and 5,000 mPa.s, can be used, having at least one reactive function, preferably at least 2, which can be placed at the end of the chain.

[0241] Polymer precursors reacting by polyaddition may include, for example, polymethylhydrosiloxane, vinylmethylsiloxane, vinyl-terminated polydimethylsiloxane (PDMS), in particular linear, vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymers, hydride-terminated polydimethylsiloxanes, hydride-terminated polyphenylmethylsiloxanes, cyclic vinylmethylsiloxane, vinyl-MQ resin, trimethylsilyl-terminated polymethylhydrosiloxane, trimethylsiloxane-terminated dimethylsiloxane copolymer, MQ resin hydride, and the like, as well as combinations thereof.

[0242] The polymeric precursors reacting by hydrolysis-polycondensation, whether they are silicone resins or silicone oils, can include for example poly(methylsilsesquioxanes), poly(propylsilsesquioxanes), poly(phenylsilsesquioxanes), polydimethylsiloxane (PDMS), trimethylsilyl-terminated polydimethylsiloxane (PDMS), hydroxyl-terminated polydimethylsiloxane (PDMS), silanol-terminated polydimethylsiloxane (PDMS), silanol-terminated polyphenylsiloxane (PDMS), silanol-terminated diphenylsiloxane-dimethylsiloxane copolymer, poly(2-acetoxyethylsilsesquioxanes), organo-modified alkoxy-silanes and their oligomers, and all similar macromolecules as well as their mixtures.

[0243] The organopolysiloxane material or polymer may also be obtained by crosslinking a mixture of one or more monomeric precursors and one or more polymeric precursors as described above, as well as one or more oligomeric precursors which may be linear, branched or cyclic. These oligomeric precursors have a lower molecular weight than the polymeric precursors. Polymeric and / or oligomeric precursors comprising a number of reactive functions as described above greater than 2, advantageously much greater than 2, may be added to the mixture as a “co-binder” in order to promote a high crosslinking density of the organopolysiloxane polymer finally obtained.

[0244] Monomeric, oligomeric and / or polymeric precursors, in particular silicone resins, copolymerized or not with an organic polymer, play the role of polymeric binder to obtain the solid organopolysiloxane polymer combined with the thermoplastics of each layer.

[0245] Silicone oil type organopolysiloxane precursors can be considered as additives if they are added in small quantity (generally between 0.1 and 5% dry) in the whole formula of a layer, independently of the other components for the formation of the solid organopolysiloxane polymer.

[0246] Crosslinking may require a catalyst:

[0247] - In the case of crosslinking of organopolysiloxanes by hydrolysis-polycon densation, the formula may include a metal catalyst, such as, for example, metal complexes based on platinum, tin, zinc, zirconium and cerium, in particular platinum-cyclovinylmethyl-silxane complexes, tin ethylhexanoate, zinc ethylhexanoate, zirconium ethylhexanoate, cerium ethylhexanoate, and tin dibutyl laurate.

[0248] - In the case of the crosslinking of organopolysiloxanes by hydrosylilation, the addition a catalyst may be necessary: ​​this may be, for example, platinum or a suitable platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0249] A crosslinking agent, for example carrying Si-H bonds, may be present.

[0250] PREFERRED ARCHITECTURES

[0251] According to a variant, the intermediate layer(s) (3b) is (are) made up of: • one or more coloring agent(s), in particular pigments and / or glitter, advantageously holograms, • one or more thermoplastic polymer(s) advantageously chosen from polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), poly-benzymidazole (PBI), polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyarylether ketone (PAEK), and mixtures thereof, • from 0 to 10% of charges, • from 0 to 20% additives, • optionally one or more silicone resin(s).

[0252] According to another variant, the intermediate layer(s) (3b) is (are) made up of: • one or more coloring agent(s), in particular pigments and / or glitter, advantageously holograms, • from 0 to 10% of charges, • from 0 to 20% additives, • one or more silicone resin(s), and • optionally one or more thermoplastic polymer(s) advantageously chosen from polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzymidazole (PBI), polyethersulfone (PES), po- lyphenylene ether sulfone (PPSU), polyarylether ketone (PAEK), and mixtures thereof.

[0253] According to another particular variant, the intermediate layer(s) (3b) is (are) made up of: • one or more coloring agent(s), in particular pigments and / or glitter, advantageously holograms, • one or more thermoplastic polymer(s) advantageously chosen from polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), poly-benzymidazole (PBI), polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyarylether ketone (PAEK), and mixtures thereof, • from 0 to 10% of charges, • from 0 to 20% additives, • one or more silicone resin(s).

[0254] According to a particular embodiment, the coating comprises two intermediate layers (3b), including at least one decorative layer. Advantageously, the layer(s) (3b) compose several decorations, one (i) comprising one or more thermochromic pigment(s) and the other (j) comprising at least one temperature reference pigment composition.

[0255] Preferably, the intermediate layer(s) (3b) only partially cover the primer layer (3a).

[0256] METAL SUBSTRATE

[0257] Advantageously, said metal substrate (2), also called support, is a substrate made of aluminum, stainless steel, cast iron or aluminum, iron, titanium or copper.

[0258] For the purposes of the present invention, aluminum means a metal consisting of 100% aluminum or an aluminum alloy.

[0259] Advantageously, the metal substrate (2) is an aluminum substrate, a stainless steel substrate or a multi-layer metal substrate. The metal substrate (2) may be a two-layer or three-layer substrate, these multi-layers being able to be obtained for example by co-lamination, by hot diffusion under load (solid State bonding) or by hot or cold impact bonding.

[0260] Preferably, the metal substrate (2) comprises an alternation of layers of metal and / or metal alloy.

[0261] According to one embodiment, the metal substrate (2) is a substrate made of aluminum alloy, stainless steel or a multilayer metal substrate whose face (2a) is made of aluminum alloy or stainless steel.

[0262] Preferably, the metal substrate (2) is an aluminum substrate.

[0263] Advantageously, the thickness of the metal substrate (2) is between 0.5 mm and 10 mm.

[0264] Advantageously, the face (2a) of the metal substrate (2) has previously undergone a surface treatment making it possible to improve the adhesion of the coating to said substrate.

[0265] According to one embodiment, the surface of the face (2a) of the metal substrate (2) has undergone a surface treatment, said surface treatment being a chemical attack, brushing, hydration, sandblasting, shot blasting, a physicochemical treatment of the plasma or corona or laser type, a chemical activation or a combination of these different techniques.

[0266] Advantageously, the face of the substrate (2a) on which the coating (3) according to the invention will be applied can be treated so as to increase its specific surface area; for an aluminum substrate, this treatment can be done by anodization (creation of a tubular alumina structure), by chemical attack, by sandblasting, by brushing, by shot blasting or by adding material by means of a technology such as thermal projection (flame, plasma or arc spray). The other metal substrates can also be polished, sandblasted, brushed, micro-blasted or receive an addition of material by means of a technology such as thermal projection (flame, plasma or arc spray).

[0267] As metallic substrates which can be used in the present invention, mention may advantageously be made of anodized or non-anodized aluminum substrates, optionally polished, brushed, sandblasted, shot-blasted or micro-blasted, anodized or non-anodized aluminum alloy substrates, optionally polished, brushed, sandblasted or micro-blasted, steel substrates, optionally polished, brushed, sandblasted, shot-blasted or micro-blasted, stainless steel substrates, optionally polished, brushed, sandblasted or micro-blasted, cast steel, aluminum or iron substrates, and copper substrates, optionally hammered or polished.

[0268] Advantageously, the substrate may be chosen from substrates comprising ferritic stainless steel / aluminum / austenitic stainless steel layers, substrates comprising stainless steel / aluminum / copper / aluminum / austenitic stainless steel layers, cast aluminum, aluminum or aluminum alloy caps lined with an outer stainless steel base, metallic co-laminated substrates, for example two-layer co-laminated substrates comprising a stainless steel layer (for example intended to constitute the inner face of the article) and a layer of aluminum or aluminum alloy, anodized or not (for example intended to constitute the outer face of the article).

[0269] Advantageously, the average arithmetic roughness Ra of the surface of the face (2a) of the metal substrate (2) is greater than or equal to 1 pm.

[0270] The arithmetic mean roughness Ra is measured using a roughness meter according to ISO 4287. Ra represents the arithmetic mean of the deviations from the mean. The surface topography can be studied in particular with a profilometer with probe equipped with a fine stylus fitted with a diamond tip, or with an optical metrology device such as Altisurf®, in which a chromatic confocal sensor allows non-contact measurement. The study of this surface topography makes it possible to define the average arithmetic roughness Ra.

[0271] METHOD

[0272] The invention also relates to a method of manufacturing a heating element coated (1) with a coating (3) for a household article according to the invention, characterized by the following steps:

[0273] a) a step of providing a metal substrate (2) comprising two opposite faces;

[0274] c) optionally, a step of treating at least one face (2a) of the metal substrate (2), to obtain a treated face (2a) promoting the adhesion of a primer layer (3a) on the support (2);

[0275] d) a step of applying the layers (3a) (3b) of the coating (3);

[0276] e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b);

[0277] f) optionally a step of cooking the element obtained in step d) or e) at a temperature between 250°C and 420°C;

[0278] g) a step of applying the finishing layer (3c) to the element obtained in step d), e) or f);

[0279] h) optionally a step of cooking the element obtained in step g) at a temperature between 250°C and 420°C.

[0280] The invention also relates to a method of manufacturing a household article comprising a heating element coated (1) with a coating (3) according to the invention, characterized by the following steps:

[0281] a) a step of providing a metal substrate (2) in the form of a substantially flat metal substrate comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22);

[0282] b) where appropriate, when a metal substrate in the form of a substantially flat metal substrate is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22), said step (b) being carried out either before step (a), or before step (d) of producing the layers (3a) and (3b) of the coating (3), or after step (f) of baking and before step (g) of producing the finishing layer or after step (g);

[0283] c) optionally, a step of treating at least one face (2a) of the metal substrate (2), to obtain a treated face (2a) promoting the adhesion of a primer layer (3a) on the support (2);

[0284] d) a step of applying the layers (3a) (3b) of the coating (3);

[0285] e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b);

[0286] f) optionally a step of cooking the element obtained in step d) at a temperature between 250°C and 420°C;

[0287] g) a step of applying the finishing layer (3c) to the element obtained in step d), e) or f);

[0288] h) optionally a step of cooking the element obtained in step g) at a temperature between 250°C and 420°C.

[0289] Advantageously, during step d), the layer(s) (3a) and (3b) is / are applied by pad printing, electrostatic powdering, spray spraying, screen printing, roller application or digital printing, preferably by spraying. Advantageously, the spraying is carried out in a solvent or aqueous phase.

[0290] Advantageously, during step g), the finishing layer (3c) is applied by electrostatic powdering, spray spraying, screen printing, spray gun, doctor blade, coating cylinder, brush, roller application or digital printing, preferably by spraying.

[0291] According to an advantageous arrangement of the invention, the finishing layer (3c) is applied to the coated support at a deposition rate of less than or equal to 5 g / m2, preferably between 0.1 and 2.5 g / m2, even more preferably between 0.2 and 2 g / m2.

[0292] Advantageously, the method according to the invention comprises a step of crosslinking g') of the finishing layer (3c) subsequent to or simultaneously with step g).

[0293] According to a variant, the crosslinking of the liquid silicone varnish composition applied to the coated support can generally be activated by heat treatment, at a temperature between 50 and 400°C, preferably between 50 and 300°C, obviously taking into account the maximum resistance of the support to heat.

[0294] Advantageously, the crosslinking (c') of the varnish is carried out at a temperature of 300°C for a duration of 10 min.

[0295] Advantageously, the higher the crosslinking temperature, the shorter the crosslinking time.

[0296] According to one embodiment, the crosslinking step c') does not require heat treatment, in particular because the support is hot at the time of application of the varnish.

[0297] Advantageously, the steps of the method according to the invention make it possible to coat the metallic support (2) by a coating (3) formed by the layers (3a), (3b) and (3c). Generally, these layers are wet when they are applied. By wet layer, it is understood within the meaning of the present invention that the layer comprises all or part of its solvents.

[0298] Shaping is also called stamping.

[0299] When the shaping step precedes the application d) of the coating, the coating is preferably carried out by spraying.

[0300] When this shaping step is subsequent to the application d) of the coating, the coating is preferably carried out by screen printing or by roller.

[0301] ARTICLE

[0302] The invention also relates to a household article comprising a heating element coated according to the invention or capable of being obtained according to the method of the invention.

[0303] According to one embodiment, this household item is a culinary item or an electrical cooking appliance and the layer (3c) forms a cooking face.

[0304] In this case, the layer (3c) is advantageously transparent.

[0305] In this case, the coloring agent of layer (3c) is advantageously glitter.

[0306] Advantageously, the culinary article (100) according to the invention is chosen from the group consisting of saucepan, frying pan, skillets or caquelons for fondue or raclette, stewpot, wok, sauté pan, crepe maker, grill, griddle, pot, casserole dish, cooker or bread machine bowl, culinary mold, molds and plates for pastry, barbecue plates and grills, preparation bowls.

[0307] According to one embodiment, the culinary article (100) comprises a heating face (6) intended to be placed in contact with an external heating source, the heating face (6) being opposite the cooking face (5) intended to be placed in contact with the food during cooking.

[0308] The culinary article according to the present invention may in particular be a culinary article of which one of the two opposite faces of the substrate is an inner face, possibly concave, intended to be arranged on the side of food likely to be introduced into or onto said article, and of which the other face of the substrate is an outer face, possibly convex, intended to be arranged towards a heat source.

[0309] Advantageously, the electric cooking appliance (200) is chosen from the group consisting of electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread maker, electric pressure cooking appliance, waffle makers, rice cookers and jam makers.

[0310] The electrical cooking appliance (200) comprises a coated cooking element (1) according to the invention and a heating source (210) configured to heat said coated cooking element (1).

[0311] According to one embodiment, the household item according to the invention is a small heating household appliance.

[0312] It may be an iron and the coated heating element is the soleplate of the iron or a hair care article and the coated heating element is one of the heating plates of said article.

Claims

Claims

1. Coated heating element (1) for a household article, comprising a metal substrate (2) coated on at least one face (2a) with a coating (3) free of fluorocarbon resin and comprising at least the following layers and in this order from the metal substrate (2): (3a) a primer layer comprising one or more aromatic or heterocyclic thermoplastic polymers; (3b) one or more intermediate layer(s) comprising one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins;(3c) a finishing layer consisting of: - an elastomer silicone obtained from at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2), and at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H), preferably in the presence of a metal catalyst; and optionally: - one or more thermoplastic polymers, and / or - one or more additive(s), and / or - one or more coloring agents, the layer (3a) being different from at least one of the layers (3b).;

2. Coated heating element (1), characterized in that the content of aromatic or heterocyclic thermoplastic polymers in the primer layer (3a) is lower than the content of aromatic or heterocyclic thermoplastic polymers in the layer(s) (3b).

3. Coated heating element (1) according to claim 2, characterized in that the content of aromatic or heterocyclic thermoplastic polymers increases from the primer layer (3a) to the last layer (3b).

4. Coated heating element (1) according to any one of the preceding claims, characterized in that the content of aromatic or heterocyclic thermoplastic polymers in the primer layer (3a) represents from 50 to 75% by weight of the primer layer (3a).

5. Coated heating element (1) according to any one of the preceding claims, characterized in that the content of aromatic or heterocyclic thermoplastic polymers in the interlayer(s) mediators (3b) represent from 75 to 100% by weight of said layer(s).

6. Coated heating element (1) according to any one of the preceding claims, characterized in that the thickness of the layer(s) (3a) and (3b) is between 1 pm and 100 pm, preferably between 2 pm and 30 pm, particularly preferably between 3 pm and 10 pm.

7. Coated heating element (1) according to any one of the preceding claims, characterized in that the organopolysiloxanes carrying reactive functions of the layer (3c) are silicone oils.

8. Coated heating element (1) according to any one of the preceding claims, characterized in that the thickness of the finishing layer (3c) is between 0.1 pm and 10 pm, preferably between 0.5 pm and 5 pm, even more preferably between 1 pm and 2 pm.

9. A coated heating element (1) according to any preceding claim, characterized in that the catalyst, if present, is platinum or a platinum-based catalyst such as Karstedt catalyst or Ashbys catalyst.

10. A method of manufacturing a household article comprising a coated heating element (1) with a coating (3) according to any one of the preceding claims, characterized by the following steps: a) a step of providing a metal substrate (2) in the form of a substantially flat metal substrate comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22);b) where appropriate, when a metal substrate in the form of a substantially flat metal substrate is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22), said step (b) being carried out either before step (a), or before step (d) of producing the layers (3a) and (3b) of the coating (3), or after step (f) of baking and before step (g) of producing the finishing layer or after step (g); c) optionally, a step of treating at least one face (2a) of the metal substrate (2), to obtain a treated face (2a) promoting the adhesion of a primer layer (3a) to the support (2); d) a step of applying the layers (3a) (3b) of the coating (3); e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b); f) optionally a step of baking the element obtained in step d) at a temperature between 250°C and 420°C; g) a step of applying the finishing layer (3c) to the element obtained in step d), e) or f); h) optionally a step of baking the element obtained in step g) at a temperature between 250°C and 420°C.

11. Method according to claim 10, characterized in that, during step g), the finishing layer (3c) is applied by electrostatic powdering, spray spraying, screen printing, spray gun, doctor blade, coating cylinder, brush, roller application or digital printing, preferably by spraying.

12. Method according to claim 10 or 11, characterized in that it comprises a step of crosslinking g') of the finishing layer (3c) subsequent to or simultaneous with step g).

13. Method according to claim 12, characterized in that the crosslinking g') of the finishing layer (3c) is carried out at a temperature of 300°C for a duration of 10 min.

14. Household article comprising a coated heating element (1) according to any one of claims 1 to 9 or obtainable according to any one of claims 10 to 13.

15. Household article according to claim 14 characterized in that it is a culinary article or an electrical cooking appliance and in that the layer (3c) forms a cooking face.

16. Household article according to claim 15, characterized in that the coloring agent of the layer (3c) is glitter.

17. Household article according to claim 14, characterized in that it is a culinary article or electrical cooking appliance and in that the layer (3c) is intended to be placed in contact with a heating source.

18. Culinary article (100) according to any one of claims 15 to 17, chosen from the group consisting of saucepan, frying pan, skillets or caquelons for fondue or raclette, stewpot, wok, sauté pan, crepe pan, grill, griddle, pot, casserole dish, cooker or bread machine bowl, culinary mold, molds and plates for baking, barbecue plates and grills, preparation bowls.

19. An electric cooking appliance (200) according to any one of claims 15 to 17, selected from the group consisting of an electric crepe maker, an electric raclette maker, an electric fondue maker, an electric grill, an electric griddle, an electric cooker, a bread maker, an electric pressure cooking appliance, waffle makers, rice cookers and jam makers.

20. Household article according to claim 14 characterized in that it is a small heating household appliance.

21. Household article according to claim 20 characterized in that it is an iron and that the coated heating element (1) is the soleplate of the iron or a hair care article and that the coated heating element is one of the heating plates of said article.

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